Non-return valve

ABSTRACT

The inventive non-return valve comprises a valve body ( 1 ) which defines an internal fluid through-opening ( 7 ) extending along the longitudinal axis ( 5 ) of the body, comprising a seat body ( 17 ) defining a valve seat ( 31 ) arranged in said through opening ( 7 ) and a closing body ( 35 ) which is axially displaceable in the through opening ( 7 ) oppositely to a closing force produced by a closing spring ( 45 ) between a closed position applied to the seat body ( 17 ) and an open position lifted from the valve seat ( 31 ) on the closing body ( 35 ), wherein the valve body ( 1 ) forms a guide along which the seat body ( 17 ) is axially displaceable in different adjusting positions corresponding to the desired preloads of the closing spring ( 45 ) and, consequently to the desired adjustments of the closing force quantity of said closing spring ( 45 ).

The invention relates to a non-return valve having a valve housing whichdefines an interior fluid passage extending along the longitudinal axisof the passage, a seat element which is positioned in the passage anddefines a valve seat, and a detent element which may be moved axiallyfor movement against the closing force of a closing spring in thepassage between a detent position adjoining the seat element and openingpositions raised above the valve seat on the detent element.

Fluid-engineering assemblies frequently contain non-return valves ascomponents of the control systems of the assemblies. It has been foundin many practical applications that control in use of non-return valveswith a fixed opening pressure is not trouble-free because of thevariable configuration of the assemblies (with regard to pressure level,volume flow, site of installation, and the like). In such a case arelevant non-return valve must be replaced with a valve set for theopening pressure adapted to the assembly when the assembly is placed inoperation on site. This entails burdensome and time-consuming conversionmeasures which in some instances must be executed repeatedly because theopening pressure required in individual cases cannot be accuratelyforeseen. A remedy could be found in this instance in the form of anon-return valve that could be adjusted as a function of the openingpressure.

Currently available adjustable non-return valves cannot, however, meetthe requirements to be set. Disclosed valves with adjustable openingpressure are configured as pressure control valves. Aside from the factthat pressure control valves are not well suited for the purpose withrespect to adjustment ranges, pressure stages, and temperature range,the chief problem encountered with pressure-control valves is that theflow of fluid is diverted at an angle of 90° downstream from theadjustment device, so that fouling particles may be deposited on thevalve seat in the event of fouling-laden fluids and may then cause thevalve to fail.

The object of the invention is to create an adjustable non-return valvewhich, like the disclosed non-return valves, operates with no deflectionof the flow of fluid (input/output and direction of action of the valveon one longitudinal axis), one in which the opening pressure may beadjusted without modifying the structural length of the valve.

It is claimed for the invention that this object is attained in the caseof a non-return valve of the type indicated in the foregoing in that thevalve housing is in the form of a guide along which the seat element maybe displaced axially into various adjustment positions which correspondto the desired prestresses of the closing spring and accordingly thedesired adjustments of the magnitude of the closing force of the closingspring.

A non-return valve with axial fluid passage is made available, one whichpermits adjustment of the opening pressure optimal for operation of theassembly, so that no replacement of the valve for adaptation isnecessary. The non-return valve may be configured for desired pressureadjustment ranges by appropriate design of the closing spring.Consequently, a non-return valve the adjustment range of which extendsover the anticipated ranges of opening pressure desired may be selectedfor installation in a suitable assembly.

In especially advantageous exemplary embodiments of the invention adisplacement device which may be actuated from the exterior of the valvehousing is provided for control of the axial adjustment positions of theseat element. It accordingly permits adjustment of the opening pressureof the valve when installed under the prevailing operating conditions,without the need for installation operations.

In exemplary embodiments distinguished by especially simple and compactdesign the interior wall of the valve housing restricting passage formsthe guide for the displaceable seat element, which is in the form of anadjustment piston having a coaxial interior passage the edge of whichfacing the detent element forms the valve seat for a detent elementhaving one valve element.

In such exemplary embodiments the displacement device which may beactuated from the exterior of the valve housing to adjust the openingpressure is configured so that the wall of the valve housing forming theguide of the adjustment piston has at least one slot opening extendingin the axial direction. A control pin extends through this opening; itsinterior end is seated in a radial hole of the adjustment piston and itsexterior section projects outside the valve housing. The configurationmay be such that the projecting outer section of the control pinoperates in conjunction with a positioning mechanism which may bedesigned in accordance with the requirements and areas of application. Amanually operated positioning device may be provided in addition to thecontrollable linear drives, a device such as a positioning nut on thevalve housing, for example.

With a configuration of the positioning device such as this twodiametrically opposite slot openings are provided, preferably in thevalve housing, for two diametrically opposite control pins of thedisplacement device. In this instance the force of displacement foradjustment processes is introduced by way of the positioning nut to twodiametrically opposite positions in the displaceable adjustment pistonsserving as seat elements, so that the adjustment processes may becarried out with precision and with no danger of canting.

By preference the displacement device has two positioning nuts betweenwhich the section of the control pins projecting outward is contained.Not only may the control pins and the adjustment piston be adjusted inboth adjustment directions, but the adjustment may be secured by lockingthe positioning nuts in a simple and reliable manner.

In advantageous exemplary embodiments the spring-loaded locking element,the valve element of which interacts with the valve seat on theadjustment piston, is guided axially displaceable on a guide elementpresent in the passage of the valve housing. The length of thedisplacement path made available for the detent element by this guide isgreat enough so that an adequate displacement path is available asopening lift of the detent element in all the adjustment positions ofthe adjustment piston involved.

By preference the displacement device, which may be operated from theexterior of the valve housing and controls the axial adjustmentpositions of the adjustment piston serving as seat element, is providedwith a display device which provides a position display and accordinglyan indication of the adjusted opening pressure. In exemplary embodimentsin which the displacement device has positioning nuts on the valvehousing provision may be made for a visible marking or scale along theexterior of the valve housing from which the location of the positioningnuts may be read.

The invention will be described below with reference to an exemplaryembodiment shown in the drawing, in which the non-return valve claimedfor the invention is shown in detail.

The single FIGURE presents on an approximately actual scale alongitudinal section of the exemplary embodiment of the non-return valveclaimed for the invention.

A valve housing 1 made of hexagonal stock has on one end an interiorscrew-in threading 3 which defines an end section of a fluid passage 7concentric with the longitudinal axis 5. Adjacent to the hexagonalsection of the valve housing 1 containing the interior threading 3 is asection 9 cylindrical both on the exterior and the interior into the endsection 11 of which a connection adapter 13 is forced which forms asecond fluid connection, an interior screw-in threading 15 beingprovided which corresponds to the screw-in interior threading 3 on theopposite end of the housing 1.

An adjustment piston 17 forming the seat element of the non-return valveis mounted in the cylindrical housing section 9 between the adapter 13and the interior threading 3 so as to be axially displaceable. Theadjustment piston 17 is sealed off from the cylinder wall of the valvehousing 1 in both of its axial end areas by means of O-rings (not shown)seated in annular grooves 19, so that the fluid passage 7 is also sealedoff from slot openings 21 which extend through the wall of the valvehousing 1. The slot openings 21 which extend in the axial direction makeavailable an axial displacement path for the control pins 23 which,diametrically opposite each other, extend through the slot opening 21,are seated in radial blind holes 25 of the adjustment piston 17, and bytheir outer end project beyond the exterior wall of the valve housing 1.The sections of the control pins 23 projecting to the exterior aresituated between two positioning nuts 27 which are screwed onto exteriorthreading positioned on the housing section 9.

The adjustment piston 17 is slightly stepped on its exterior and isconfigured geometrically such that the O-rings seated in the annulargrooves 19 are not damaged when it is installed in the valve housing 1.

The adjustment piston 17 has a coaxial interior passage 29 the edge ofthe opening of which facing the screw-in interior threading 3 forms avalve seat 31 in the form of a conical surface which interacts with acorresponding valve cone 33 on the detent element 35.

The detent element 35 is mounted so as to be axially displaceable on aguide element 37 which has a guide pin 39 which is concentric with thelongitudinal axis 5 and is engaged in a concentric blind hole 41 in thedetent element 35. On the end facing away from the guide pin 39 theguide element 37 has arms 43 extending radially, the radially exterioredge of which is provided with exterior threading by means of which theguide element 37 is anchored on the interior threading 3 of the valvehousing 1. A helical compression spring 45 generating the closing forceby which the valve cone 33 of the detent element 35 is pressed againstthe valve seat 31 on the adjustment piston 17 is mounted between thearms 43 of the guide element 37 and the thickening of the detent element35 forming the valve cone 33.

The FIGURE illustrates the adjustment position of the adjustment piston17 serving as seat element in the position corresponding to the lowestopening pressure. If axial displacement of the adjustment piston 17upward (corresponding to the FIGURE) is effected by rotation of thepositioning nuts 27 by way of the control pins 23, the detent element 35is moved along against the closing force of the compression spring 45,so that the spring tension and accordingly the closing force areincreased. The adjustment path of the adjustment piston 17 andaccordingly the greatest possible opening pressure which may be set aredefined by the axial length of the slot openings 21. It is essential forthe length of the blind hole 41 into which the guide pin 39 of the guideelement 37 is introduced to make an adequate guide length available, sothat an adequate displacement path of the detent element 35 is stillavailable for the opening stroke even when the adjustment piston 17 isin the end position of the displacement path.

The non-return valve claimed for the invention offers an axial fluidpassage, so that, since no rerouting of the flow is required, noproblems resulting from depositing of particles need be feared if fouledfluids are involved. The structural elements of the non-return valve maybe made of stainless steel, so that the valve is also suitable foraggressive media. A position marking or scale may be mounted on theexterior of the valve housing 1 in order to provide a display of theposition of the adjustment piston 17. The valve may be preset fordesired opening pressure values if calibrated markings or scales arepresent.

1. A non-return valve having a valve housing (1) which defines aninterior fluid passage (7) extending along the longitudinal axis (5) ofsuch housing, having a seat element (17) situated in the passage (7) anddefining a valve seat (31), and having a detent element (35) which ismovable axially for movement against the closing force of a closingspring (45) in the passage (7) between a detent position adjoining theseat element (17) and opening positions raised above the valve seat (31)on the seat element (17) [sic], characterized in that the valve housing(1) forms a guide along which the seat element (17) may be displacedaxially into different adjustment positions which correspond to thedesired pretensioning of the closing spring (45) and accordingly todesired adjustments of the magnitude of the closing force of the closingspring (45).
 2. The non-return valve as claimed in claim 1, wherein adisplacement device (23, 27) actuatable from the exterior of the valvehousing (1) is provided for control of the axial adjustment positions ofthe seat element (17).
 3. The non-return valve as claimed in claim 1,wherein the interior wall of the valve housing (1) delimiting thepassage (7) forms the guide for the displaceable seat element, which isin the form of an adjustment piston (17) which has a coaxial interiorpassage (29) the edge of which facing the detent element (35) forms thevalve seat (31) for a detent element (35) having a valve cone (33). 4.The non-return valve as claimed in claim 2, wherein the wall of thevalve housing (1) forming the guide of the adjustment piston (17) has atleast one slot opening (21) which extends in the axial direction andthrough which extends a control pin (23) which is part of thedisplacement device and the interior end of which is seated in a radialhole of the adjustment piston (17) and the exterior section of whichprojects from the exterior of the valve housing (1).
 5. The non-returnvalve as claimed in claim 4, wherein the valve housing (1) has, in thearea having the slot opening (21), an exterior threading for at leastone positioning nut (27) belonging to the displacement device, which nutinteracts with the section of the control pin (23) projecting from thevalve housing (1) for adjustment of the axial position of the adjustmentpiston (17).
 6. The non-return valve as claimed in claim 5, wherein twodiametrically opposite slot openings (21) are provided in the valvehousing (1) for two diametrically opposite control pins (23) of thedisplacement device.
 7. The non-return valve as claimed in claim 6,wherein the displacement device has two positioning nuts (27) betweenwhich the outward projecting section of the control pins (23) isreceived.
 8. The non-return valve as claimed in claim 1, wherein thereis provided in the passage (7) of the valve housing (1) a guide element(37) with fluid passages and on which the detent element (35) is guidedso as to be axially displaceable.
 9. The non-return valve as claimed inclaim 8, wherein the guide element (37) has a guide pin (39) whichextends concentrically with the longitudinal axis (5) and which isintroduced into a concentric blind hole (41) of the detent element (35),which hole is open on the end of the detent element (35) facing awayfrom the valve cone (33) and wherein the blind hole (41) is of an axiallength permitting displacement movement of the detent element (35) intocorresponding open positions relative to the guide pin (39).
 10. Thenon-return valve as claimed in claim 7, wherein there is provided asclosing spring a helical compression spring (45) which is insertedbetween the guide element (37) and the detent element (35).
 11. Thenon-return valve as claimed in claim 10, wherein the guide element (37)has, on the end opposite the guide pin (39), radially extending arms(43) which are provided for anchoring on the valve housing (1) and onwhich the facing end of the helical spring (45) is supported.